Tow sticks



1960 B. WIRKKALA 2,949,972

TOW srxcxs Filed Jan. 3, 1959 BENJAMIN W/RKkALA United Snares iPatent t;

TOW STICKS Benjamin Wirkkala, Naselle, Wash.

Filed Jan. 3, 1958, Ser. No. 706,981

2 Claims. (Cl. 18019) This invention relates to what are generallyreferred to as tow sticks; such sticks being used for the manual towingof small airplanes as, for example, from a hangar into or from a landingstrip or from place to place in a hangar.

It is the principal object of this invention to provide a tow stick thatis powered in such manner as to eliminate the requirement in its use formanual towing, as heretofore required.

Tow sticks, which are of that particular character to which the presentimprovement is applied, are primarily intended for the moving of thosesmall airplanes which are equipped with a forward wheel, locatedapproximately below the forward end of the fuselage and with twolaterally spaced rear wheels; such airplanes having a weight that iswithin the range between 1500 and 3000 pounds. Tow sticks, as heretoforeused, are equipped with means at one end for the quick and easyattachment to the hub member of the front wheel of the airplane and atthe other end have a handle which is grasped by the workman for thetowing operation.

In view of the fact that it is sometimes quite difiicult to manually toweven a light weight airplane, especially against a wind, it has been theobject of the present invention to provide a tow stick that carries apower driven means that can be caused, after a towing connection hasbeen made, to drive the forward wheel of the plane thus to move theairplane forwardly, leaving it only necessary for the workman holdingthe stick to employ it as a means for guiding the airplane as thusmoved.

More specifically stated, the present invention resides in providing atow stick with a friction wheel that may be engaged with the front wheelof the airplane, after a towing connection has been made, and a motor orpower device whereby the friction wheel can be driven to impart drivingforce to said front Wheel of the airplane for moving it forwardly.

A further object of the invention is to provide the present powered towstick with wheels whereby it can be easily and readily rolled from planeto place after the fashion of pushing a wheel barrow.

Still further objects and advantages reside in the details ofconstruction of the various parts of the tow stick; in their combinationand in their mode of use, as will hereinafter be fully described.

In accomplishing the above mentioned and other objects of the invention,I have provided the improved details of construction, the preferredforms of which are illustrated in the accompanying drawings, wherein:

Fig. 'l is a side view of an airplane to which a powered tow stickembodying the improvements of the present invention has been attachedfor a towing operation.

Fig. 2 is a side view of the tow stick when detached from the airplaneand resting in rolling position on the surface.

Fig. 3 is a top or plan view of the tow stick.

Fig. 4 is an enlarged sectional detail showing the means are forconnecting the tow stick to the axle of the front wheel for towing.

Fig. 5 is an enlarged cross-section taken on line 55 in Fig. 3.

Fig. 6 is a cross-section taken on line 6-6 in Fig. 4.

Referring more in detail to the drawings:

In Fig. 1, I have designated the front end portion of an airplane, whichis typical of those with which the present tow stick is to be used, byreference numeral 10.

The front supporting wheel which is here shown to be fitted with arubber tire, is designated by reference numeral 12. while 13 designatesthe front wheel mounting yoke. The purpose of this wheel is to coactwith rear wheels, not shown, for the support of the airplane for landingand in take-off and also when towed, as for example, into and from thehangar.

The wheel 12, \as shown in Fig. 4, is mounted for rotation on a tubularaxle 15, that is fixed at its opposite ends in and extends through thelaterally spaced legs 13a 13b of the yoke 13. It is with these endportions of the axle 15 that the tow stick connections are made fortowing, as presently will be explained.

The present tow stick comprises a rather elongated handle portion 18,preferably of tubular construction and equipped with a transverse handlebar or handhold 19 at its forward end. At its rearward end it terminatesin two laterally spaced legs 2020, and these are equipped at the outsideof their end portions with paired wheels 2l 21, of a size about one-halfthat of wheel 12, or smaller, on which the tow stick can be rolled fromplace to place as has been indicated in Fig. 3.

Mounted by the tow stick, near its wheel equipped, or rearward endportion is an electric motor 25. This is fixed upon a base plate 26 thatis movably supported for limited forward and rearward movement betweenthe spaced leg portions 20-20 of the tow stick. The motor 25 operatesthrough a suitable reduction gear contained in a housing designated at27 in Fig. 3, to drive a small belt wheel 28 that is fixed to a drivenshaft 29 extended from the gear reduction housing, as seen in Fig. 5. Abelt 30 operates about belt wheel 28 to drive a larger belt wheel 31that is fixed on a cross-shaft 32 on which a friction wheel 33 is fixed.Wheel 33 is located in the central longitudinal plane of the tow stick,and its mounting shaft 32 is rotatably carried by the rearward ends of apair of upwardly and rearwardly directed brackets 34-34 that are locatedat opposite sides of the motor in parallel, vertical planes and arerigidly fixed along their lower edges to the base plate 26, as bestshown in Fig. 5. This wheel is about one-half the diameter of wheel 12.It is shown in Fig. 5 that the plate 26 is supported at its oppositelongitudinal edges for limited forward and rearward sliding movement inchannel bars 3535 that are fixed to the inside surfaces of the legportions 2020 of the tow stick. This movement permits wheel 33 to bemoved from contacting position with wheel 12 when this is desired, or tobe pressed against the wheel for driving.

Also mounted on the base plate 26 as carried between the forward endportions 20-20 of the tow stick, is an electric storage battery 40 forpowering the motor 25. Current from the battery to the motor iscontrolled by a switch 41 which, preferably, is fixed to the stickadja-- cent the handle bar where it is readily accessible to the user ofthe stick. Circuit connections would be made in conventional mannerbetween motor and battery.

In lieu of drawing electrical energy from the battery 40 for driving themotor, the necessary electrical energy might .be supplied from thestorage battery of the airplane by plugging in a circuit connectiontherewith as indicated by the dotted line showing of parts at 42 in Fig.1.

Under favorable conditions, the friction wheel 33, as

supported on the slidably mounted plate 26 and pressed under its ownweight, aided by its tendency of crawl up on the wheel 12, will maintain-a non-slipping driving connection with the wheel 12. However, to insureagainst slippage and also to serve as a means for drawing the frictionwheel 33 clear of the wheel 12 to stop driving or to facilitate themaking of a towing connection, I have provided a lever means forshifting plate 26 forwardly or rearwardly in its supports. This levermeans comprises a stiff rod 50 that extends along the tow bar, and whichat its rearward end has pivotal connection as at 51 with the near edgeof the plate 26 and its forward end has pivotal connection, as at 53,with a hand lever 54 that has a pivotal mounting 55 on the stick. Thearrangement of parts is such that when the lever 54 is swung to itsforward position, the plate 26 will be shifted forwardly and wheel 33will be cleared from the wheel 12 and when swung rearwardly, the plate26 will be shifted rearwardly and the wheel 33 pressed against wheel 12for driving.

The means for and manner of connecting the rearward ends of the legportions 20-49 of the tow stick with the axle 15 of the wheel 12 is bestshown in Fig. 4, which shows the connection at one side; the other sidebeing the same. It is here indicated that the ends of the laterallyspaced legs 20-20 have pins 60 mounted therein in axial alignment, forlimited endwise movement; the pins being slidably contained in tubularsleeves 61 that are fixed in the legs 26 in axial alignment. Bell cranklevers 62 are pivoted, as at 63, on the legs. One arm of each bell crankhas pin and slot connections as at 64 with the inner end of thecorresponding pin. Cables 65 extend from the other arms of these bellcranks into and along the tubular stick to its forward end and are thereconnected to an exposed knob or hand hold 66. Springs 67, containedunder compression in the sleeves 61 which mount the pins, urge the pinsinwardly to extend them into the ends of axle 15 to elfect a towingconnection.

To aid in moving the tow stick from place to place, it is equipped atthe end of its leg portions 26-40 with the small supporting wheels21-21. These wheels, as seen in Fig. 4, are revoluble on the extendedouter ends of the tubular sleeves 61-61 in which the pins are slidablycontained.

Also, to aid in the attaching of the stick to the wheel axle, it isequipped beneath the frame structure or rearwardly thereof with a shortleg 70. By swinging the forward end of this tow stick downwardly fromthe normal rolling position after the stick has been positioned forconnection, this leg can be engaged with the ground. Then by fartherdownward movement, the rearward end of the tow stick will be swungupwardly and the pins as carried therein can thus be easily brought toproper level and moved into alignment with the axle ends.

To connect the tow stick with the axle, the cables 65 are first pulledforwardly by grasping the knob 66. This rocks the bell crank levers 62and pulls the inner ends of the pins into the sleeves 61. The stick ismoved to a position that will bring the legs 29-450 along opposite sidesof wheel 12 and the pins into alignment with the open opposite ends ofthe tubular axle 15, as indicated in Fig. 3. The knob is then releasedallowing the springs 67 to actuate the pins inwardly into the open endsof the tubular axle. Thus, the towing connection is made.

After this connection has been made the lever 54 is swung rearwardly,thus through the connecting rod or link 50 to move the wheel 33 againstwheel '12 in a friction engaged driving connection. The motor 25 is thenenergized to drive the wheel 33, thus to move the airplane forwardly. Asthe plane moves forwardly, it is A guided by means of the tow stickwhich has fixed steering connection with the wheel axle.

To release the stick, the lever 54 is pulled forwardly to disengage thefriction wheel 33 from the wheel 12. Then the pins 6060 are releasedfrom the ends of axle 15 by pull on the hand hold or knob 65. The stickthen drops for rolling support on wheels 69-69 and can be wheeled clearof the airplane.

Devices of this kind may employ various other means for driving thefriction wheel 33, and various other means than hereinshown for makingthe towing connection without departing from the spirit of theinvention. What is believed to be the essence of the invention is theapplication of power to the stick itself for driving the wheel 12regardless of other features of the invention.

A small engine might be substituted for use in lieu of an electricmotor.

It is anticipated that the mounting axles 15 of different airplanesmight not all conform to the tubular form herein shown. For example, theaxle might be solid. In such instances, the pins 60 would be formed attheir ends with suitable means for effecting holding connections withthe axle ends. This might require that the pins be equipped with opensockets to receive the axle ends, or it might be required that they haveadapter fittings of various kinds applied thereto to accommodate thepins. Therefore, the present invention is not to be restricted to usewith the specific form of axle 15 illustrated.

These devices also may be made applicable to larger types of airplanesmerely by provision of adequate power and suitable means for effectingthe towing connection bet-ween stick and wheel axle.

What I claim as new is:

l. A tow stick for an airplane having a tow wheel mounted on a tubularaxle; said tow stick having hand hold means at its outer end, and havinglaterally spaced leg portions at its inner end adapted to receive saidairplane towing wheel and axle between them; said leg portions beingequipped with adjustable means whereby releasable towing connections maybe made with the opposite end portions of said tubular axle, a motordriven friction wheel mounted on said stick and a manual means at thefor-ward end of the stick for causing said friction wheel to be shiftedinto and from driving contact with the airplane wheel, and ground wheelsof lesser diameter than said airplane wheel mounted on the inner end ofthe tow stick coaxial of the means for making the towing connections forrolling support of the tow stick in moving it into and from place ofuse; said adjustable means for making said towing connections comprisingmeans mounted by said leg portions and movable into and from the endportions of said tubular axle and manual means operable from the forwardend of said stick for effecting adjustment of the connecting means.

2. The device of claim 1 wherein fulcrum members, in the form ofsupporting legs are fixed to the tow stick in transverse alignment,between its ends for ground contact in positioning the connecting meansin alignment with the axle ends for connection therewith.

References Cited in the file of this patent UNITED STATES PATENTS2,166,450 Smalley July 18, 1939 2,287,955 Zunino June 30, 1942 2,409,552Donnellan Oct. 15, 1946 2,751,990 Finlay et al June 26, 1956 2,773,703Ferguson et al. Dec. I l, 1956 2,815,875 Benson Dec. 10, 1957

